1. Field of the Invention
The present invention relates to a working fluid which comprises plural halogenated hydrocarbons and is used in air conditioners and heat pumps and the like.
2. Description of the Related Art
Hitherto, as working fluids in air conditioners, heat pumps and the like, are used halogenated hydrocarbons derived from methane or ethane, which are also called as fluorinated halocarbons. They work at such utilization temperature that a condensation temperature and/or an evaporation temperature are from about 0 (zero) to about 50.degree. C. Among them, chlorodifluoromethane (CHClF.sub.2, R22) with a boiling point of -40.8.degree. C. is widely used as a working fluid in an air conditioner for a building and a large size refrigeration system.
Recently, depletion of the ozone layer in the stratosphere with the fluorinated halocarbon is seriously discussed as one of global environmental problems, and amounts to be used and produced of some fully halogenated chlorofluorocarbons (CFCs) which have high ozone depletion potential are limited by the Montreal Protocol. In future, their use and production will be banned.
R22 has an ozone depletion potential (hereinafter referred to as "ODP") of 0.05 when ODP of trichlorofluoromethane (CCl.sub.3 F, R11) is defined to be 1 (one). Though R.sub.22 is not a CFC, its production and use are expected to increase and it is expected that R22 will have significant influences on the human living in future, since the air conditioners and the heat pumps are and will be widely used. Therefore, it is highly desired to quickly develop a working fluid which has a small ODP and can be used as a substitute for R22.
U.S. Pat. No. 4,810,403 to Vivens et al discloses, as a substitute for dichlorodifluoromethane (R12, boiling point of -29.8.degree. C.), a refrigerant comprising a first halocarbon having a boiling point at atmospheric pressure in the range of about -50.degree. C. to about -30.degree. C., a second halocarbon having a boiling point at atmospheric pressure in the range of about -30.degree. C. to about -5.degree. C. and a third halocarbon having a boiling point at atmospheric pressure in the range of about -5.degree. C. to 30.degree. C., which has substantially the same vapor pressure as R12. One example of the refrigerant composition is a mixture of R22, R152a and R114. This patent does not suggest any composition which can be used as a substitute for R22.